BACKGROUND ＆ AIMS : Most of the patients with irritable bowel syndrome (IBS) and eating disorder (ED) may develop their symptoms since they are in middle teen ages. However, the prevalence and the features of adolescent IBS and ED were generally lacking. The objective of this research was to investigate the epidemiological features of adolescent IBS and ED in Japan.SUBJECTS ＆ METHODS : We randomly selected Junior high school students in Miyagi prefecture, Japan according to population of the districts within Miyagi. The recovery rate was 76.9%, and a total of 833 boys and 888 girls (age : 15 y.o.) participated in this study. They fulfilled self-reported questionnaires those include Rome-II Modular Questionnaire (RIIMQ), Self-reported IBS Questionnaire (SIBSQ) based on Rome-II criteria, Generalized Self-Efficacy Scale (GSES), SF-36, Eating Attitude Test (EAT)-26 and other questions on their personal lives.RESULTS : One hundred and six boys (12.7%) and 145 girls (16.3%) were diagnosed as IBS by RIIMQ. Students with IBS had lower scores in GSES and every SF-36 subscales than control students those without abdominal symptoms (boys: n=214, girls: n=148). IBS students had sleep disturbance more often than controls. IBS students had more traumatic episodes and felt their personal lives more stressful than controls. IBS girls had more frequent traumatic episodes and felt more stressful in their lives than IBS boys. A total of 21boys (2.5%) and 47 girls (5.3%) were diagnosed as ED by EAT-26. They also showed more impairment in health-related QOL, sleep disturbance, traumatic episodes and perceived stress than controls, but not self-efficacy.CONCLUSION : Prevalence and some features of adolescent IBS and ED have unique characters. Early intervention may be important for them.